Method and device for transmitting and receiving data by using multiple carriers in mobile communication system

ABSTRACT

To solve the above-mentioned problem, the method for transmitting and receiving a signal by user equipment (UE) through one or more cells, according to one embodiment of the present specification, comprises the steps of: receiving, from a base station, a first message indicating whether one or more cells usable by the UE are enabled; determining which cells to enable or disable on the basis of the first message; and enabling or disabling the selected cells. According to the embodiment of the present specification, by aggregating carriers amongst different base stations, a possibility for the UE to transmit and receive high-speed data through carrier aggregation can increase.

CROSS REFERENCED TO RELATED APPLICATIONS AND CLAIM OF PRIORITY

This application is a continuation of application Ser. No. 15/339,876,filed Oct. 31, 2016, which is a continuation of U.S. patent applicationSer. No. 14/400,308, which is the National Stage of InternationalApplication No. PCT/KR2013/003921, filed May 6, 2013, now U.S. Pat. No.9,485,765, which claims the benefit of Provisional Application No.61/644,645, filed May 9, 2012, Provisional Application No. 61/645,591,filed May 10, 2012, Provisional Application No. 61/646,888, filed May14, 2012, Provisional Application No. 61/649,910, filed May 21, 2012,Provisional Application No. 61/653,026, filed May 30, 2012, andProvisional Application No. 61/658,617, filed Jun. 12, 2012, thedisclosures of which are incorporated herein by reference into thepresent disclosure as if fully set forth herein.

BACKGROUND 1. Field

The present invention relates to a multicarrier-based datatransmission/reception method and apparatus for use in a mobilecommunication system.

2. Description of Related Art

Mobile communication systems were developed to provide mobile users withcommunication services. With the rapid advance of technologies, themobile communication systems have evolved to the level capable ofproviding high speed data communication service beyond the earlyvoice-oriented services.

Recently, standardization for a Long Term Evolution (LTE) system, as oneof the next-generation mobile communication systems, is underway in the3^(rd) Generation Partnership Project (3GPP). LTE is a technology forrealizing high-speed packet-based communications with the data rate ofup to 100 Mbps, which is higher than the currently available data rate,and its standardization is almost complete.

In line with the completion of the LTE standardization, an LTE-Advanced(LTE-A) system is now under discussion, which improves a transfer rateby combining the LTE communication system with several new technologies.One of such technologies is Carrier Aggregation. The Carrier Aggregationis a technology allowing a terminal to use multiple downlink carriersand multiple uplink carriers unlike the conventional technology of usingone downlink carrier and one uplink carrier for data communication.

Currently, the LTE-A is featured with the intra-eNB carrier aggregationonly. This restricts applicability of the carrier aggregation functionso as to a problem of failing aggregation of macro and pico or femtocells in a scenario where a plurality of pico or femto cells and a macrocell operate in an overlapped manner.

SUMMARY

The present invention has been conceived to solve the above problem andaims to provide an inter-eNB carrier aggregation method and apparatus.

In accordance with an aspect of the present invention, a communicationmethod of a terminal which transmits/receives signals through one ormore cells includes receiving a first message for instructingactivation/deactivation of the cells available for the terminal from abase station, selecting a cell to be activated or deactivated based onthe first message, and activating or deactivating the selected cell.

In accordance with another aspect of the present invention, acommunication method of a base station which transmits/receives signalsthrough one or more cells includes selecting a cell to be activated ordeactivated for signal communication with the terminal and transmittinga first message notifying whether to activate one or more cells for useby the terminal based on information determined, wherein the terminaldetermines the cells to be activated or deactivated based on the firstmessage and activates or deactivates the determined cells.

In accordance with another aspect of the present invention, a terminalwhich transmits/receives signals through one or more cells includes atransceiver which transmits and receives signals to and from a basestation and a controller which controls the transceiver to receive afirst message for instructing activation/deactivation of the cellsavailable for the terminal from a base station, selects a cell to beactivated or deactivated based on the first message, and activates ordeactivates the selected cell.

In accordance with still another aspect of the present invention, a basestation which transits/receives signals through one or more cellsincludes a transceiver which transmits and receives signals to and froma terminal and a controller which controls the transceiver, selects acell to be activated or deactivated for signal communication with theterminal, and controls transmitting a first message notifying whether toactivate one or more cells for use by the terminal based on informationdetermined, wherein the terminal determines the cells to be activated ordeactivated based on the first message and activates or deactivates thedetermined cells.

The data transmission method and apparatus of the present invention isadvantageous in that a terminal is capable of increasing the probabilityof fast data transmission/reception through carrier aggregation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating the architecture of an LTE systemaccording to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a protocol stack of the LTE systemaccording to an embodiment of the present invention.

FIG. 3 is a diagram illustrating the normal carrier aggregation.

FIG. 4 is a diagram illustrating the inter-eNB carrier aggregation.

FIG. 5 is a signal flow diagram illustrating the operations of the UEand the eNB for configuring a SCell belonging to the primary set.

FIG. 6 is a diagram illustrating operations of UE and eNB forconfiguring a SCell belonging to a non-primary set.

FIG. 7 is a diagram illustrating an exemplary RRC control messageincluding SCell configuration information.

FIG. 8 is a diagram illustrating another exemplary RRC control messageincluding SCell configuration information.

FIG. 9 is a diagram illustrating a format of the AD MAC CE.

FIG. 10 is a diagram illustrating the procedure ofactivating/deactivating the primary set and non-primary set servingcells according to an embodiment of the present invention.

FIG. 11 is a diagram illustrating the procedure ofactivating/deactivating the primary set and non-primary set servingcells according to another embodiment of the present invention.

FIG. 12 is a diagram illustrating a procedure of activating anddeactivating SCells using the first and second A/D MAC CEs.

FIG. 13 is a diagram illustrating an alternative procedure ofactivating/deactivating the SCells.

FIG. 14 is a flowchart illustrating the UE operation of activating theprimary and non-primary sets serving cells

FIG. 15 is a diagram illustrating the PUCCH SCell configurationprocedure.

FIG. 16 is a flowchart illustrating the UE operation of configuring andactivating the PUCCH SCell.

FIG. 17 is a flowchart illustrating the UE operation of configuring andactivating the non-primary set serving cells.

FIG. 18 is a diagram illustrating the procedure of acquiring systeminformation in the primary set and non-primary set serving cell.

FIG. 19 is a diagram illustrating an alternative procedure of acquiringsystem information through primary set serving cell and non-primary setserving cell.

FIG. 20 is a flowchart illustrating the UE operation ofacquiring/monitoring system information of the primary set serving celland non-primary set serving cell.

FIG. 21 is a flowchart illustrating an alternative UE operation ofmonitoring the system information change in association with the primaryset serving cell and non-primary set serving cell.

FIG. 22 is a diagram illustrating a procedure of adding primary set andnon-primary set serving cells using the configuration complete MAC CE.

FIG. 23 is a flowchart illustrating the UE operation which has receivedthe RRC connection reconfiguration message in the primary set servingcell and non-primary set serving cell.

FIG. 24 is a block diagram illustrating the UE.

FIG. 25 is a block diagram illustrating the eNB

DETAILED DESCRIPTION

Exemplary embodiments of the present invention are described withreference to the accompanying drawings in detail.

Detailed description of well-known functions and structures incorporatedherein may be omitted to avoid obscuring the subject matter of thepresent invention. This aims to omit unnecessary description so as tomake the subject matter of the present invention clear.

For the same reason, some of elements are exaggerated, omitted orsimplified in the drawings and the elements may have sizes and/or shapesdifferent from those shown in drawings, in practice. The same referencenumbers are used throughout the drawings to refer to the same or likeparts.

Detailed description of well-known functions and structures incorporatedherein may be omitted to avoid obscuring the subject matter of thepresent invention. Exemplary embodiments of the present invention aredescribed with reference to the accompanying drawings in detail. Priorto the description of the present invention, the LTE system and carrieraggregation are explained briefly.

FIG. 1 is a diagram illustrating the architecture of an LTE systemaccording to an embodiment of the present invention.

Referring to FIG. 1, the radio access network of the mobilecommunication system includes evolved Node Bs (eNBs) 105, 110, 115, and120, a Mobility Management Entity (MME) 125, and a Serving-Gateway(S-GW) 130. The User Equipment (hereinafter, referred to as UE) 135connects to an external network via eNBs 105, 110, 115, and 120 and theS-GW 130.

In FIG. 1, the eNBs 105, 110, 115, and 120 correspond to the legacy nodeBs of the UMTS system. The eNBs allow the UE 135 to establish a radiochannel and are responsible for complicated functions as compared to thelegacy node B. In the LTE system, all the user traffic including realtime services such as Voice over Internet Protocol (VoIP) are providedthrough a shared channel and thus there is a need of a device toschedule data based on the state information such as buffer states,power headroom states, and channel states of the UEs; and the eNBs 110,115, and 120 are responsible for this. Typically, one eNB controls aplurality of cells. In order to secure the data rate of up to 100 Mbps,the LTE system adopts Orthogonal Frequency Division Multiplexing (OFDM)as a radio access technology. Also, the LTE system adopts AdaptiveModulation and Coding (AMC) to determine the modulation scheme andchannel coding rate in adaptation to the channel condition of the UE.The S-GW 130 is an entity to provide data bearers so as to establish andrelease data bearers under the control of the MME 125. The MME 125 isresponsible for mobility management of UEs and various control functionsand may be connected to a plurality of eNBs.

FIG. 2 is a diagram illustrating a protocol stack of the LTE systemaccording to an embodiment of the present invention.

Referring to FIG. 2, the protocol stack of the LTE system includesPacket Data Convergence Protocol (PDCP) 205 and 240, Radio Link Control(RLC) 210 and 235, Medium Access Control (MAC) 215 and 230, and Physical(PHY) 220 and 225. The PDCP 205 and 240 is responsible for IP headercompression/decompression, and the RLC 210 and 235 is responsible forsegmenting the PDCP Protocol Data Unit (PDU) into segments inappropriate size for Automatic Repeat Request (ARQ) operation. The MAC215 and 230 is responsible for establishing connection to a plurality ofRLC entities so as to multiplex the RLC PDUs into MAC PDUs anddemultiplex the MAC PDUs into RLC PDUs. The PHY 220 and 225 performschannel coding on the MAC PDU and modulates the MAC PDU into OFDMsymbols to transmit over radio channel or performs demodulating andchannel-decoding on the received OFDM symbols and delivers the decodeddata to the higher layer.

FIG. 3 is a diagram illustrating the concept of intra-eNB carrieraggregation.

Referring to FIG. 3, an eNB transmits and receives signals throughmultiple carriers across a plurality of frequency bands. For example,the eNB 305 can be configured to use the carrier 315 with centerfrequency f1 and the carrier 310 with center frequency f3. If carrieraggregation is not supported, the UE 330 has to transmit/receive datausing one of the carriers 310 and 315. However, the UE 330 having thecarrier aggregation capability can transmit/receive data using both thecarriers 310 and 315. The eNB can increase the amount of the resource tobe allocated to the UE having the carrier aggregation capability inadaptation to the channel condition of the UE so as to improve the datarate of the UE 330. The technique of aggregating the downlink and uplinkcarriers respectively for transmission and reception at one eNB isreferred to as intra-eNB carrier aggregation. In any case, however,there may be a need of aggregating the downlink/uplink carriers ofdifferent eNBs.

FIG. 4 is a diagram illustrating the inter-eNB carrier aggregationaccording to an embodiment of the present invention.

Referring to FIG. 4, the eNB 1 405 uses the carrier 410 with centerfrequency f1 for transmission/reception, and the eNB 2 415 uses thecarrier 420 with center frequency f2 for transmission/reception. If thedownlink carrier 410 with the center frequency f1 and the downlinkcarrier 420 with the center frequency f2 are aggregated, this means thatcarriers transmitted by more than one eNB are aggregated for one UE.This is referred to as inter-eNB Carrier Aggregation (CA) in the presentinvention.

The terms used frequently in the present invention are describedhereinafter.

Assuming that a cell is configured with one downlink carrier and oneuplink carrier in the conventional concept, the carrier aggregation canbe understood as if the UE communicates data via multiple cells. Withthe use of carrier aggregation, the peak data rate increases inproportion to the number of aggregated carriers.

In the following description, if a UE receives data through a certaindownlink carrier or transmits data through a certain uplink carrier,this means to receive or transmit data through control and data channelsprovided in cells corresponding to center frequencies and frequencybands characterizing the carriers. In the present Invention, carrieraggregation may be expressed as configuring a plurality of serving cellswith the use of terms such as primary cell (PCell), secondary cell(SCell), and activated serving cell. These terms are used as they are inthe LTE mobile communication system and specified in TS36.331 andTS36.321 (December, 2011).

In the present invention, the serving cells controlled by the same eNBare defined as a set of serving cells. The set may is classified intoone of a primary set and a non-primary set. The primary set is the setof serving cells controlled by the eNB controlling the PCell (primaryeNB), and the non-primary set is the set of serving cells controlled bythe eNB not controlling the PCell (non-primary eNB). The eNB maynotifies the UE whether a serving cell belongs to the primary set ornon-primary set in the process of configuring the corresponding servingcell. One UE can be configured with one primary set and one or morenon-primary set.

In the following description, the terms ‘primary set’ and ‘non-primaryset’ may be substituted by other terms to help understanding. Forexample, the terms ‘primary set,’ ‘secondary set,’ ‘primary carriergroup,’ and ‘secondary carrier group’ may be used. Even in such a case,however, it should be notice that although the terms are different butused in the same meaning.

FIG. 5 is a signal flow diagram illustrating the operations of the UEand the eNB for configuring a SCell belonging to the primary setaccording to an embodiment of the present invention.

Referring to FIG. 5, in the mobile communication system made up of theUE 505, the eNB 1 515, and the eNB 2 510, the cell 1 to cell 3 arecontrolled by the eNB 1 515; and the fourth and fifth cells are controlby the eNB 2 510. Suppose that the PCell of the UE is the cell 1 and theeNB 1 515 configures the Cell 2 as an additional SCell to the UE 505. Inthe following description, the eNB 515 controlling the PCell, i.e. theprimary set, is referred to as serving eNB. The eNB 510 which is not theserving eNB 515 and controls the serving cell of the UE is referred toas drift eNB. That is, the eNB 515 controlling the serving cells of theprimary set is the serving eNB 515, and the eNB 510 controlling theserving cells of the non-primary set is the drift eNB 510. The servingeNB 515 and the drift eNB 510 may be referred to as the primary eNB 515and non-primary eNB 510, respectively.

The serving eNB 515 sends the UE a control message called RRC ConnectionReconfiguration including the information on the SCell to be added newlyto the UE at step 520. The SCells to be added newly are managed by theserving eNB 515 directly and information thereon is included in thecontrol message as shown in table 1.

TABLE 1 Name Description sCellIndex-r10 Serving cell identifier of aninteger with a predetermined size. Used in updating information on thecorresponding serving cell in the future. cellIdentification-Information for use in identifying the serving cell physically and r10composed of downlink center frequency and Physical Cell ID (PCI)radioResource Information on radio resource of service cell, e.g.downlink ConfigCommon bandwidth, downlink Hybrid ARQ (HARQ) feedbackchannel SCell-r10 configuration information, uplink center frequencyinformation uplink bandwidth information. radioResource Information onUE-specific resource allocated in the serving cell, ConfigDedicated e.g.channel quality measurement reference signal structure SCell-r10information and inter-carrier scheduling configuration information.Timing Information indicating TAG to which UE belongs. For example, itAdvance Group may be composed of TAG id and Timing Advance (TA) timer.If (TAG) the UE belongs to P-TAG, this information may not be signaled.information

The Timing Advance Group (TAG) is a set of the serving cells sharing thesame uplink transmission timing. A TAG is classified into one of PrimaryTAG (P-TAG) and Secondary TAG (S-TAG). The P-TAG includes the PCell, andS-TAG includes SCells without PCell). If a certain serving cell belongsto a certain TAG, this means that the uplink transmission timing of theserving cell is identical with those of the other serving cellsbelonging to the TAG and whether the uplink synchronization is acquiredis determined by means of the Timing Advance (TA) timer of the TAG. Theuplink transmission timing of a certain TAG is set through a randomaccess process in a serving cell belonging to the TAG and maintainedwith the receipt of TA command. The UE starts or restart the TA timer ofthe corresponding TAG whenever the TA command for the corresponding TAGis received. If the TA timer expires, the UE determines that the uplinktransmission synchronization of the corresponding TAG has broken andthus suspends uplink transmission until the next random access occurs.

At step 525, the UE 505 transmits a response message in reply to thecontrol message based on the message received at step 520.

The UE 505 establishes forward/downlink synchronization with the Cell 2,i.e. serving cell 1, at step 530. The forward/downlink is oftransmitting from the eNB to the UE, and the reverse/downlink is oftransmitting from the UE to the eNB. In the present invention, the termsare used interchangeably. If the downlink synchronization is establishedin a certain cell, this means that the synchronization channel of thecell is acquired so as to check the downlink frame boundary.

The serving eNB 515 may send the UE 505 a command to activate the SCell1 at a certain time when determined that the UE has completed theconfiguration of the SCell 1 at step 535. The SCell 1 activation commandmay be Activate/Deactivate MAC Control Element (A/D MAC CE) as a MAClayer control command. The control command is structured in the form ofa bitmap of which the first bit corresponds to the SCell 1, the secondbit to SCell 2, and the n^(th) bit to SCell n. The bitmap may be thesize of 1 byte. In this case, 7 indices, i.e. from 1 to 7, are used insuch a way of mapping the second Least Significant Bit (LSB) to theSCell 1, the third LSB to SCell 2, and the last LSB or the MostSignificant Bit (MSB) to SCell 7, without use of the first LSB.

The UE 505 starts monitoring the physical control channel (carryingPhysical Downlink Control Channel (PDCCH) and uplink/downlinktransmission resource allocation information) of the SCell after theelapse of a predetermined period from the receipt of the SCell 1activation command at step 535. If the SCell has been acquiredsynchronization and belonged to a TAG already, the downlink/uplinktransmission starts since then. That is, if the downlink transmissionresource allocation information is received on the PDCCH, the UEreceives downlink data but ignores the uplink transmission resourceinformation although it has bene received. If the SCell belongs to anon-synchronized TAG, the UE waits for the receipt of ‘random accesscommand’ on PDCCH in a SCell belonging to the TAG. The random accesscommand is a value of a predetermined field of the uplink transmissionresource allocation information to instruct the UE 505 to transmit apreamble in a serving cell. The Carrier Indicator Field of the randomaccess command may carry the identifier of the serving cell for preambletransmission.

The UE 505 receives a random access command instructing to transmit arandom access preamble in the serving cell 1.

The UE 505 monitors PDCCH of the PCell to receive Random Access Response(RAR) in reply to the preamble after transmitting the preamble throughthe SCell 1 at step 545. The RAR may include TA command and othercontrol information. If the preamble is transmitted by the serving eNB515, it is likely to be efficient to send the response in replay to thepreamble through the PCell in various aspects. For example, since theRAR is received only through the PCell, it is possible to reduce thePDCCH monitoring load of the UE. Accordingly, the UE 505 monitors thePDCCH of the PCell to receiving RAR at step 550.

If a valid response message is received in reply to the preamble, the UE505 assumes that it is possible to transmit uplink signal transmissionafter the elapse of a predetermined period from that time point. Forexample, if the valid RAR is received at the subframe n, it isdetermined that the uplink transmission is possible from the subframe(n+m).

FIG. 6 is a diagram illustrating operations of UE and eNB forconfiguring a SCell belonging to a non-primary set.

In this embodiment, the eNB 1 615 is referred to as a serving eNB, andthe eNB 2 610 as a drift eNB.

Referring to FIG. 6, the serving eNB 615 determines to add a cell of thedrift eNB 610 as a serving cell at step 620. Depending on theembodiment, this determination may be performed in such a way that theserving eNB 615 adds a SCell to the UE 605 at a certain time point. Inan embodiment, if the UE 605 is located within an area of the cell underthe control of the eNB 2 610, the serving eNB 615 may determine to addthe cell under the control of the eNB 2 610 as the SCell. Thisdetermination may be made based on the data amount which the UE 605transmits/receives.

The serving eNB 615 sends the eNB 2 610 a control message requesting foradding a SCell at step 625. In an embodiment, the control message mayinclude at least one of the following information.

TABLE 2 Name Description SCell id information Information related toidentifiers of SCells to be configured by the drift eNB. Formed with oneor more sCellIndex-r10. Determined by the serving cell and notified tothe drift eNB to prevent the identifier in use by the serving eNB frombeing reused. The ranges of SCell id used by the serving eNB and thedrift eNB may be defined separately. For example, SCell ids 1~3 may bedefined in advance for use in serving eNB while SCell ids 4~7 for use indrift eNB. TAG id information Information related to identifier of TAGto be configured by the drift eNB. Defined by the serving eNB andnotified to the drift eNB to prevent the identifier in used by theserving eNB from being reused. UL scheduling Include priorityinformations of logical channels and logical information channel groupinformation configured to the UE. The drift information interprets theUE buffer state report information and performs uplink scheduling usingthis information. Inform on bearer to be It is preferred that the drifteNB processes the service requiring offloaded large amount datatransmission/reception, e.g. FTP download. The serving eNB determinesthe bearer to be offload to the eNB among the bearers configured to theUE and sends the drift eNB the information on the bearer to beoffloaded, e.g. DRB identifier, PDCP configuration information, RLCconfiguration information, required QoS information. Call accept controlThe serving eNB provides the drift eNB with reference informationinformation for use in determining whether to accept SCell add request.For example, this information may include required data rate, expecteduplink data amount, and expected downlink data amount.

If the SCell add request control message is received, the drift eNB 610determines whether to accept the request in consideration of the currentload status. In an embodiment, the step of determining whether to acceptthe request is referred to as Call Admission Control.

If it is determined to accept the request, the drift eNB 610 generates acontrol message including at least one of the following information andtransmits the control message to the serving eNB 615.

TABLE 3 Name Description SCellToAddMod Information related to SCellsconfigured by the drift eNB as follows. sCellIndex-r10,cellIdentification-r10, radioResourceConfigCommonSCell-r10,radioResourceConfigDedicatedSCell-r10, TAG-related information PUCCHinformation At least one of SCells belonging to the non-primary set isfor PUCCH SCell configured with Physical Uplink Control Channel (PUCCH).Uplink control information such as HARQ feedback, Channel StatusInformation (CSI), Sounding Reference Signal (SRS), and SchedulingRequest (SR) may be transmitted. Hereinafter, the SCell in which PUCCHis transmitted is referred to as PUCCH SCell. The PUCCH SCell identifierand PUCCH configuration information are the sub-informations of thisinformation. Information for data Logical channel (or logical tunnel)for use in data exchange forwarding between the serving eNB and drifteNB. May include GPRS Tunnel Protocol (GTP) tunnel identifier fordownlink data exchange and GTP tunnel identifier for uplink dataexchange. UE identifier C-RNTI for use by UE in SCells of non-primaryset. Hereinafter, referred to as C-RNTI_NP Bearer configurationConfiguration information on the bearer to be offloaded. May informationinclude list of bearers accepted to be offloaded and per-bearerconfiguration information. If the bearer configurations are identical,it is possible to include only the list of bearers accepted.

If the control message of step 630 is received at step 630, the servingeNB 615 sends the UE 605 a message instructing to add the serving cellat step 635. Depending on the embodiment, the serving eNB 615 may sendsthe UE 605 the control message using a RRC control message. The RRCcontrol message may include at least one of the following information.

TABLE 4 Name Description SCellAddMod This may include the informationtransmitted from the drift eNB to the serving eNB as it was. That is,this is identical with SCellAddMod in table 3. The SCellAddMod isincluded per SCell and is sub-information of SCellAddModList. PUCCHinformation This may include the information transmitted from the drifteNB for PUCCH SCell to the serving eNB as it was. That is, this isidentical with PUCCH information for PUCCH SCell in table 3. Non-primarySCell List This is the information on the SCells belonging to the non-primary set among the SCells to be configured. This may be theidentifiers of the SCells or the TAGs belonging to the non- primary set.UE identifier This is C-RNTI for use by the UE in the serving cell ofthe non- primary set. Offload bearer This is the information on thebearers to be processed by the drift information eNB. This is theinformation on the bearers to be transmitted/received through theserving cells of the non-primary set in view of the UE and, if thebearer lists and bearer configurations are different, may include bearerconfiguration information.

The RRC control message may include the configuration information onmultiple SCells. The RRC control message also may include theconfiguration of the primary and non-primary sets serving cells. Forexample, if Cell 2, Cell 3, Cell 4, and Cell 5 are configured as theSCells of the UE having the Cell 1 as its PCell, the RRC control messagemay include the above informations arranged in various orders asexemplified in FIG. 7. Referring to FIG. 7, the Cell 1 and Cell 2 havethe same uplink transmission timing to form the P-TAG, the Cell 3 formsthe S-TAG 1, and the Cell 4 and Cell 5 form the S-TAG 2.

The RRC control message contains SCellToAddModList 705 includingSCellToAddMod 710 for Cell 2, SCellToAddMod 715 for Cell 3,SCellToAddMod 720 for Cell 4, and SCellToAddMod 725 for Cell 5. TheSCellToAddMod may include specific information or not depending on thecharacteristic of the corresponding SCell. If the SCell belongs to theP-TAG, i.e. if the SCell has the same uplink transmission timing as thePCell, the corresponding SCellToAddMod does not include the informationrelated to the TAG. For example, the SCellToAddMod for the Cell 2 doesnot include the information about TAG. The SCellToAddMod for each of theSCells belonging to the rest TAGs includes the TAG identifier and TAtimer value for the TAG to which the corresponding SCell belongs. Theinformation on at least one of the cells belonging to the non-primaryset may include the non-primary set information 730, e.g. non-primaryset identifier and C-RNTI for use by the UE in the non-primary set. Inthe example of FIG. 7, the SCellToAddMod for the Cell 4 includes thenon-primary set information. The information on one of the cellsbelonging to the non-primary set includes the PUCCH configurationinformation 735. In the example of FIG. 7, the SCellToAddMod for theCell 4 includes the above information. To the SCell which belongs to thenon-primary set but has no information on the non-primary set, theinformation on the non-primary set of the SCell having the same TAG id.For example, although the information on the Cell 5 includes nonon-primary set information, the UE is capable of determining that theCell 5 belongs to the non-primary set based on the non-primary setinformation of the Cell 4 having the same TAG id and uses thenon-primary set identifier and C-RNTI, which are identical with those ofthe Cell 4, for the Cell 5.

FIG. 8 is a diagram illustrating another example of arranging the TAGinformation and the non-primary set information at a location other thanSCellToAddMod.

The RRC control message carries the SCellToAddModList 805 includingSCellToAddMod 810 for Cell 2, SCellToAddMod for Cell 3, SCellToAddModfor Cell 4, and SCellToAddMod for Cell 5. The SCellToAddMod contains thesame type of information. That is, every SCellToAddMod may includesCellIndex-r10, cellIdentification-r10, andradioResourceConfigCommonSCell-r10.

The TAG information 815, the non-primary set information 820, and thePUCCH configuration information of PUCCH SCell are included separately.The TAG information 815 may include the TAG identifiers, identifiers ofthe SCells forming the TAG, and TA timer value. For example, the TAGinformation 815 may include the information 830 notifying that the TAGhaving the TAG identifier 1 includes the SCell 2 and the TA timer is setto the value t1 and the information 835 notifying that the TAG havingthe TAG identifier 2 includes the SCell 3 and SCell 4 and the TA timeris set to the value t2.

The non-primary set information 820 may include the per-non-primary setidentifiers, identifiers of the serving cells included in the set, andC-RNTI for use in the corresponding set. For example, the information840 indicating that the non-primary set having the set identifier 1includes the SCell 3 and SCell 4 and uses the C-RNTI x. The primary setinformation is not signaled explicitly but determined according to thefollowing rule.

Primary Set Information Determination Rule

Serving cells belonging to primary set: PCell and SCells not belongingto any non-primary set.

C-RNTI for use in primary set: C-RNTI in use in current PCell.

The non-primary set information may include the TAG identifier otherthan the SCell identifier. This is possible under the assumption thatthe set and TAG are formed such that one TAG is not formed acrossmultiple sets. For example, the non-primary set configurationinformation 820 includes the information indicating the TAG id 2 insteadof the information indicating the SCell 3 and SCell 4 in order for theUE to determine that the SCell 3 and SCell 4 having the TAG id 2 belongto the non-primary set.

The PUCCH SCell's PUCCH configuration information is made up ofnon-primary set identifier, PUCCH SCell identifier, and PUCCHconfiguration information. Each non-primary set has one PUCCH SCell. TheCSI information for the serving cells belonging to the non-primary setand HARQ feedback information is transmitted on the PUCCH configured tothe PUCCH SCell.

The PUCCH SCell can be determined according to a predetermined rulewithout signaling PUCCH SCell identifier explicitly. For example, theSCell corresponding to the first SCellToAddMod of the SCellToAddModListmay be determined as the PUCCH SCell. Also, the SCell having the highestor lowest SCell identifier among the SCells of which informationincludes the SCellToAddMod information in the corresponding RRC controlmessage may be determined as the PUCCH SCell. Such an implicitdetermination method can be used under the assumption that only onenon-primary set exists.

The UE 605 sends the serving eNB 615 a response message at step 640.

The UE 605 establishes downlink synchronization with newly configuredSCells at step 645.

The UE 605 acquires System Frame Number (SFN) of the PUCCH SCell amongthe newly configured SCells at step 650. The SFN may be acquired in theprocedure of receiving the system information, i.e. Master InformationBlock (MIB). Depending on the embodiment, the SFN is an integerincrementing by 1 at every 10 ms in the range from 0 to 1023. The UE 605checks the PUCCH transmission timing of the PUCCH SCell using the SFNand PUCCH configuration information.

Afterward, the UE waits until the SCells are activated. If downlink dataor a predetermined control message instructing to activate SCell isreceived from the serving eNB 615 at step 655, the drift eNB 610 startsa procedure of activating the SCells. The serving eNB 615 sends thedrift eNB a downlink data forwarding request at step 655.

The drift eNB 610 may transmit a message for activating at least one ofthe SCells at step 660. In this embodiment, the drift eNB 610 sends theUE 605 the A/D MAC CE instructing to activate the SCell 3. If the MAC CEis received at the subframe n, the UE 605 activates the SCell atsubframe (n+m1). However, since the uplink synchronization of the PUCCHSCell is not acquired yet at the subframe (n+m1), both the downlink anduplink transmission/reception are not possible although the SCell hasbeen activated. That is, the UE 605 monitors PDCCH of the SCell but mayignore the downlink/uplink resource allocation signal although it isreceived.

The drift eNB 610 sends the UE 605 a random access command to establishuplink synchronization with the PUCCH SCell at step 665. Upon receipt ofthis command, the UE 605 initiates random access procedure in the PUCCHSCell using the dedicated preamble indicated by the command.

The UE 605 sends the drift eNB 610 a preamble in the SCell at step 670.The UE 605 also monitors PDCCH to receive the RAR in response to thepreamble. In this embodiment, if the UE 605 has transmitted the preamblethrough the primary set, the RAR is transmitted to the UE 605 throughthe PCell. Otherwise if the preamble has been transmitted through anon-primary set, the UE 650 monitors PDCCH of the SCell through whichthe preamble has been transmitted or the PDCCH of PUCCH SCell. This isbecause there is a need of supplementary information exchange betweenthe drift base station 610 and the serving eNB 615 to process the RAR inthe PCell. The RAR may be received with the C-RNTI to be used in thenon-primary set. It is more efficient to transmit the response messagewith the C-RNTI because the UE 605 also has been allocated the C-RNTIand there is no probability of malfunctioning caused by collision due tothe use of the dedicated preamble (i.e. since the eNB knows the UE towhich the RAR has to be transmitted based on the dedicated preamble). Ifthe valid response message is received through the SCell in which thepreamble has been transmitted or the PUCCH SCell, the UE 605 adjusts theuplink transmission timing of the PUCCH SCell and the TAG to which thePUCCH SCell based on the TA command of the response message andactivates uplink at a predetermined time point. If the valid TA commandor the valid random access response message is received at the subframen, the predetermined timing becomes the subframe (n+m2). Here, m2 is apredetermined integer.

In an embodiment, if the inter-eNB carrier aggregation is applied, theeNBs 610 and 615 may manage different serving cells. For example, theactivation/deactivation of a serving cell x is in charge of the eNB awhile the activation/deactivation of a serving cell y is in charge ofthe eNB b. Since the current A/D MAC CE designed in consideration onlythe intra-eNB carrier aggregation uses one bitmap carrying the statusinformations of all serving cells, if the serving cells are managed bymultiple eNBs, the eNB cannot write the information of the A/D MAC CEcorrectly.

FIG. 9 is a diagram illustrating a format of the AD MAC CE.

Referring to FIG. 9, the A/D MAC CE includes a MAC sub-header andpayload. The MAC sub-header may include at least one of a LogicalChannel ID (LCID) indicating the type of the payload and E bitindicating whether another MAC sub-header exists. The payload is abitmap of 1 byte of which each bit indicates the activated state of thecell corresponding to the SCell index. In more detail, the C7 bit of thebit map indicates the state of the serving cell of which SCell index is1 (hereinafter, the serving cell of which SCell index is x is referredto as SCell x), the C6 bit indicates the state of the SCell 6, and theC1 bit indicates the state of the SCell 1.

For example, it is assumed that the SCell 1 to SCell 3 910 are theserving cells controlled by the serving eNB, i.e. serving cells of theprimary set, and the SCell 4 to SCell 7 905 are the serving cellscontrolled by the drift eNB, i.e. the serving cells of the non-primaryset. In order to instruct the UE to activate/deactivate a serving cellusing the current A/D MAC CE, the serving eNB may inquire of the drifteNB about the state of the serving cell, and the drift eNB may inquireof the serving eNB about the stat of the serving cell.

FIG. 10 is a diagram illustrating the procedure ofactivating/deactivating the primary set and non-primary set servingcells according to an embodiment of the present invention.

Referring to FIG. 10, SCell 1, SCell 2, SCell 4, and SCell 5 areconfigured to the UE 1005 at a certain time point at step 1020. TheSCell 1 and SCell 2 are the serving cells of the primary set, and theSCell 4 and SCell 5 are the serving cells of the non-primary set.

At step 1025, the SCell 1 and SCell 2 are in the deactivated, and theSCell 4 and SCell 5 are in the activated state.

The serving eNB 1015 determines to activate the SCell 1 at step 1030.The serving eNB 1015 sends the drift eNB 1010 a SCell state requestcontrol message at step 1035. According to an embodiment, the controlmessage may be transmitted to the drift eNB 1010 at a certain timepoint. The control message may include a UE identifier and a SCell indexfor use in checking the SCell state.

The drift eNB 1010 generates a SCell state report control messageincluding the state information of the SCells, i.e. the SCells of thenon-primary set, which it controls among the SCells of the UE 1005 andsends this message to the serving eNB 1015 at step 1045.

The serving eNB 1015 generates the A/D MAC CE including the stateinformation of the serving cells configured to the UE 1005 and sends theA/D MAC CE to the UE 1005 at step 1050. The content of the A/D MAC CEmay be determined based on the message received at step 1045. In anembodiment, the serving eNB 1015 determines to activate the SCell 1 andthus the payload of the A/D MAC CE to be transmitted is formed asfollows.

C₇ C₆ C₅ C₄ C₃ C₂ C₁ R 0 0 1 1 0 0 1 0

That is, the serving eNB 1015 is capable of set the C1 and C2 as thestate informations of the serving cells which it manages to appropriatevalues. The appropriate values may be determined depending on whetherthe SCell 1 and SCell 2 are activated. The serving eNB 1015 sets the C4and C5 as the state information of the serving cell which the drift eNB1010 manages to the values notified in the SCell state report messagereceived at step 1045 and the rest bits to a predetermined value, e.g.0.

The UE 1005 activates the SCells instructed to activate in the receivedA/D MAC CE and deactivates the SCells instructed to deactivate in thereceived A/D MAC CE at step 1055. At this time, the bits which are notrelated to the configured SCells, e.g. the values of C7, C6, and C3 areignored.

According to an embodiment of the present invention, the UE may checkthe set to which the serving cell through which the A/D MAC CE has beenreceived belongs instead that the eNB inquires of the counterpart eNBthe active/deactivated information of the corresponding cell. FIG. 11shows the entire operation.

FIG. 11 is a diagram illustrating the procedure ofactivating/deactivating the primary set and non-primary set servingcells according to another embodiment of the present invention.

Referring to FIG. 11, the serving eNB 1115 configures the SCell 1 andSCell 2 to the UE 1105 at a certain time point at step 1120. In thisembodiment, the SCell configuration is performed using the RRCconnection reconfiguration message of step 520 of FIG. 5. In thisembodiment, when the RRC connection reconfiguration has no informationnotifying that the serving cells to be added belongs to the non-primaryset, the UE 1105 assumes that the newly added SCell 1 and SCell 2 arethe serving cells of the primary set.

Afterward, the serving eNB 1115 determines to add a serving cell underits control to the UE 1105 at a certain time point at step 1121. Theserving eNB 1115 sends the drift eNB 1110 a control message requestingto add the SCell. The serving eNB 1115 generates the controls messageincluding the information for use by the drift eNB 1110 in selecting theSCell index. This information may be a list of the SCell indices in useby the serving cell 1115 or a list of the SCell indices available foruse by the drift eNB 1110. The drift eNB 1110 may select a SCell indexbased on this information.

The drift eNB 1110 performs Call Admission Control and, if it isaccepted to add the SCell, determines the SCell-related parameters atstep 1122. For example, the drift eNB 1110 may determine the SCell indexto be used in the SCell of the drift eNB 1110 using the information foruse in selecting the SCell index which has been transmitted by theserving eNB 1115.

At step 1124, the drift eNB 1110 sends the serving eNB 1115 a SCell AddAccept control message including the information determined at step1122. In this embodiment, it is assumed that the drift eNB 1110configures two SCells of which SCell indices are SCell 4 and SCell 5.

The serving eNB 1115 sends the UE 1105 a predetermined control message,e.g. RRC connection reconfiguration, to configure the SCell 4 and SCell5 under the control of the drift eNB 1110 at step 1125. If the controlmessage of step 1125 is received, the UE 1105 configures the SCellsbased on the received message. In this embodiment, the UE 1105configures the SCell 4 and SCell 5. The control message includes atleast one of the information notifying that the SCell 4 and SCell 5belong to the non-primary set and the information notifying that theSCell 4 and SCell 5 are under control of an eNB which is not the servingeNB.

The serving eNB 1115 determines to activate the SCell 1 at step 1130.The activation determination may be made at a certain time point. Forexample, if the channel state of the SCell 1 improves or if the trafficincreases at the UE 1105, the serving eNB 1115 can make such adetermination.

The serving eNB 1115 set C1 and C1 as the information on the servingcells, i.e. SCell 1 and SCell 2, for use in determining whether toactivate/deactivate to appropriate values and R bit to 0 at step 1135.Next, the serving eNB 1115 sends the UE 1105 the A/D MAC CE in which thebits corresponding to the SCells not under its control to apredetermined value, e.g. 0. In the drawing of this embodiment, the bitsof the SCells not under its control are expressed by x for conveniencepurpose. Depending on the embodiment, the R bit may be set to analternative value.

If the A/D MAC CE is received, the UE 1105 determines whether theserving cell through which the A/D MAC CE has been received belongs tothe primary set or the non-primary set at step 1140. In interpreting theinformation of the A/D MAC CE received through the primary set servingcell, the UE checks only the information on the serving cells belongingto the primary set, i.e. C1 and C2, for activation/deactivationoperation and ignores the rest bits. For example, although C4 and C5 areset to 0 or 1, the state information on the SCell 4 and SCell 5 are notreflected. In this embodiment, the UE 1105 received the A/D MAC CE anddetermines whether to activate or deactivate the corresponding cellbased on the activation information for the SCell under the control ofthe eNB which has transmitted the A/D MAC CE among the activationinformations of the SCells written in the received A/D MAC CE. The drifteNB 1110 determines to activate the SCell 4 at step 1145. Thisdetermination may be made at a certain time point and, in more detail,based on at least one of the state of the cell under the control of thedrift eNB 1110 and the traffic condition of the UE 1105.

At step 1150, the drift eNB 1110 sets the informations on the servingcells determined to activate/deactivate, i.e. C4 and C5 of SCell 4 andSCell 5, to an appropriate value and R bit to 0. The drift eNB 1110 alsosends the UE 1105 the A/D MAC CE including the bits which correspond tothe SCells not under its control and which are set to a predeterminedvalue, e.g. 0. In the drawing of this embodiment, the bits of the SCellsnot under its control are expressed by x for convenience purpose.Depending on the embodiment, the R bit may be set to an alternativevalue.

If the A/D MAC CE is received, the UE 1105 determines whether theserving cell through which the A/D MAC CE has been received belongs tothe primary set or the non-primary set. In an embodiment, wheninterpreting the information of the A/D MAC CE received through thenon-primary set serving cell, the UE checks only the information on theserving cells belonging to the non-primary set, i.e. C4 and C5, foractivation/deactivation operation and ignores the rest bits withoutinterpretation. For example, although C1 and C2 are set to 0 or 1, thestate information on the SCell 1 and SCell 2 are not reflected.

In an alternative embodiment, it is possible for the UE to discriminatebetween the A/D MAC CE for the primary set and the A/D MAC CE for thenon-primary set by LCID instead of determining the operation based onthe set through which the A/D MAC CE has been received. For example, itis possible to define the first A/D MAC CE for the primary set servingcells and the second A/D MAC CE for the secondary set serving cells. Thefirst and second A/D MAC CEs may be determined differently in orderdepending on the embodiment, and the determined order may be shared inadvance or signaled using an explicit message.

In an embodiment, the first A/D MAC CE and the second MAC CE may beidentified by the LCID. The LCID of the first A/D MAC CE may be 11011identical with that of the conventional A/D MAC CE, and the LCID of thesecond A/D MAC CE may be set to a reserved value, e.g. 11010. The firstand second A/D MAC CEs may be, in format, identical with or differentfrom each other. The second A/D MAC CE is made up of two bytes, thefirst byte for C7-C1 and the second byte for information indicatingwhich non-primary set is targeted by the second A/D MAC CE.

If the set targeted by the A/D MAC CE is identified by the LCID, theserving eNB may activate or deactivate the serving cell of thenon-primary set depending on the case. Also, the drift eNB may activateor deactivate the serving cell of the primary set.

FIG. 12 is a diagram illustrating the procedure of activating anddeactivating SCells using the first and second A/D MAC CEs.

Referring to FIG. 12, steps 1220, 1221, 1222, 1223, 1225, and 1230 maybe performed in the similar to or identical manner with steps 1120,1121, 1122, 1123, 1125, and 1130 of FIG. 11.

The serving eNB 1215 sends the UE 1205 the first A/D MAC CE at step1235.

The serving eNB 1215 sets C1 and C2 as the informations on serving cellsdetermined to activate/deactivate, i.e. SCell 1 and SCell 2, toappropriate values and the R bit to 0. The serving eNB 1215 also setsthe bits corresponding to the SCells that are not under its control to apredetermined value, e.g. 0. The serving eNB 1215 sets the LCID of theMAC sub-header to a value indicating the first A/D MAC CE and transmitsthe A/D MAC CE to the UE 1205. In the drawing of this embodiment, thebits of the SCells not under its control are expressed by x forconvenience purpose but may be set to one of 0 and 1.

If the first A/D MAC CE transmitted by the serving cell 1215 is receivedat step 1235, the UE 1205 interprets only the information on the servingcells belonging to the primary set, i.e. C1 and C2, to performactivation/deactivation and ignores the rest bits withoutinterpretation. For example, although C4 and C5 are set to 0 or 1, theinformation is not reflected to the state of the SCell 4 and SCell 5.Depending on the embodiment, the first A/D MAC CE may be receivedthrough the serving cell of a non-primary set.

The drift eNB 1210 determines to activate the SCell 4 at step 1245.Depending on the embodiment, this determination is made at a certaintime point based on the communication state of the cell under thecontrol of the drift eNB 1210 or the communication load at the UE 1205.

At step 1250, the drift eNB 1210 sets the informations on the servingcells determined to activate/deactivate, i.e. C4 and C5 of SCell 4 andSCell 5, to an appropriate value and R bit to 0. The R bit may be setvariably depending on the embodiment. The drift eNB also sets the bitscorresponding to the SCells that are not under its control to anappropriate value, e.g. 0. The drift eNB sets the LCID of the MACsub-header to a value indicating the second A/D MAC CE and transmits theA/D MAC CE to the UE 1205. In the drawing of this embodiment, the bitsof the SCells not under its control are expressed by x for conveniencepurpose but set diversely depending on the embodiment.

If the second A/D MAC CE is received at step 1250, the UE 1210interprets the informations on only the serving cells belonging to thenon-primary set, i.e. C4 and C5, to activate/deactivate correspondingserving cells and ignores the rest bits without interpretation. Forexample, although C1 and C2 are set to 0 or 1, the above information isnot reflected to the states of the SCell 1 and SCell 2. At this time,the UE 1210 assumes that the PUCCH SCell is in the activated statealways without interpreting the bit corresponding to the PUCCH SCell.

FIG. 13 is a diagram illustrating an alternative procedure ofactivating/deactivating the SCells.

Referring to FIG. 13, the drift eNB 1310 and the serving eNB 1315 selectthe SCell index without consideration on whether the corresponding indexis in use in another set. Accordingly, one SCell index may be allocatedto one or more serving cells, and the UE 1305 determines which servingcell the SCell index indicates based on the type of the A/D MAC CE orthe serving cell through which the A/D MAC CE has been received.

In this embodiment, the serving eNB 1315 controls the cells a and b, andthe drift eNB 1310 controls the cells c and d. In an embodiment, step1320 may be executed in the same manner as or similar manner to step1120 of FIG. 11.

The serving eNB 1315 sends the drift eNB 1310 a control messagerequesting for adding SCell at step 1321.

The drift eNB 1310 determines whether to add the serving cell and, if itis determined to add the serving cell, determines the parameters relatedto the serving cell at step 1322. The drift eNB 1310 may not considerwhether a certain index is used in another eNB in determining the SCellindex to be applied to the serving cell. In this embodiment, if thedrift eNB 1310 has an algorism of allocating the SCell index in anascending order, it allocates the SCell index 1 and SCell index 2 to thenewly added serving cells, i.e. cell c and cell d. at this time, thedrift eNB 1310 may allocates a predetermined index to the PUCCH SCell.In an embodiment, if the SCell index of the PUSCH SCell is fixed to 0,there is no need of signaling the SCell index of the PUCCH SCellexplicitly.

The drift eNB 1310 sends the serving eNB 1315 a SCell Add Accept controlmessage at step 1323.

The serving eNB 1315 sends the UE 1305 a message including theinformation for use in adding the SCell at step 1325. Depending on theembodiment, this message may be transmitted through the RRC connectionreconfiguration control message.

The serving eNB 1315 determines to activate the SCell 1 at step 1330.The SCell activation may be determined based on the channel state ortraffic of the UE 1305.

The serving eNB 1315 sends the UE 1305 an A/D MAC CE at step 1335. Theserving eNB 1315 sets C1 and C2 as the information on serving cellsdetermined to activate/deactivate, i.e. SCell 1 and SCell 2, toappropriate values and the R bit to 0. Depending on the embodiment, theR bit may be set variably. The serving eNB 1315 sets the bitscorresponding to the SCells that are not under its control to apredetermined value, e.g. 0. Depending on the embodiment, the A/D MAC CEmay be a normal A/D MAC CE or the first A/D MAC CE including specificLCID.

At step 1340, the UE 1305 receives the A/D MAC CE transmitted at step1335. The UE 1305 determines whether the serving cell through which theA/D MAC CE has been received is a primary set serving cell or anon-primary set serving cell and, if serving cell is a primary setserving cell, activates/deactivated only the primary set serving cellsbased on the content of the A/D MAC CE. That is, when two SCell 1 areconfigured to the UE 1305, if the serving cell through which the A/D MACCE has been received is the primary set serving cell, the SCell 1 of theprimary set is activated or deactivated. If the first A/D MAC CE hasbeen received, only the primary set serving cells areactivated/deactivated based on the content of the A/D MAC CE.

The drift eNB 1310 determines to activate the SCell 2 at step 1345.Whether to activate or not is determined based on the channel state orthe traffic of the UE 1305.

The drift eNB 1310 sends the UE 1310 an A/D MAC CE at step 1350. The A/DMAC CE may be the normal A/D MAC CE or the second A/D MAC CE including aspecific LCID. At this time, the drift eNB 1310 sets the bitcorresponding to the PUCCH SCell to a predetermined value, e.g. 0.

If the A/D MAC CE is received at step 1350, the UE 1305 determines theset of which serving cells are to be activated or deactivated based onthe serving cell through which the A/D MAC CE has been received or thetype of the A/D MAC CE. In this embodiment, the UE 1305 assumes that thePUCCH SCell is always in the activated state so as to ignore the bitcorresponding to the PUCCH SCell.

FIG. 14 is a flowchart illustrating the UE operation of activating theprimary and non-primary sets serving cells.

The UE receives an A/D MAC CE at step 1405.

The UE determines whether the non-primary set has been configured atstep 1407. Depending on the embodiment, the UE may determine whether anyserving cell of the non-primary set has been configured. Depending onthe embodiment, the UE determines whether any serving cell which isunder the control of an eNB which is not the primary eNB (the eNBcontrolling the PCell of the UE).

If any non-primary set serving cell has been configured, the proceduregoes to step 1410 and, otherwise if any non-primary set is notconfigured or if all serving cells are controlled by one eNB, step 1425.

The UE determines whether the A/D MAC CE is related to the primary setat step 1410. This determination can be made in various methods.

Method 1

If the A/D MAC CE has been received through the primary set servingcell, the A/D MAC CE is related to the primary set and, otherwise if theA/D MAC CE has been received through a non-primary set serving cell, theA/D MAC CE is related to the non-primary set.

Method 2

If the received A/D MAC CE is the first A/D MAC CE, the A/D MAC CE isrelated to the primary set and, otherwise if the A/D MAC CE is thesecond A/D MAC CE, the A/D MAC CE is related to the non-primary set.

If the received A/D MAC CE is related to the primary set, the proceduregoes to step 1415 and, otherwise if the A/D MAC CE is related to thenon-primary set, step 1420.

The UE checks the valid bits among C1 to C7 of the payload of thereceived A/D MAC CE at step 1415. The UE determines the bits in whichthe SCell indices match among the SCells configured in the primary setas the valid bits and activates or deactivates the corresponding SCellsbased on the information of the valid bits. For example, if the SCell 1and SCell 2 are configured in the primary set, C1 and C2 are valid bits.If a certain SCell x is activated, this means at least one of thefollowing operations is performed.

Monitor PDCCH of SCell x

Start reporting Channel Status Indication (CSI, information downlinkchannel condition and control information for MIMO operation) for SCellx

Start SRS transmission in SCell x

Start transmitting Uplink Shared Channel (UL-SCH, data channel carryinguplink signal) in SCell x

If a certain SCell x is deactivated, this means stopping at least one ofthe above operations.

The UE starts or restarts sCellDeactivationTimer of the SCell which isinstructed to be activated by the valid bit. The triggered time istransmitted to the primary set serving cell. The sCellDeactivationTimeris the timer for deactivating the SCell automatically if there is notscheduling for the corresponding SCell during a predetermined period.

The sCellDeactivationTimer for the SCell which is instructed to bedeactivated by the valid bit may be stopped.

If at least one SCell is activated by the A/D MAC CE, the UE triggersPower Headroom Report (PHR), which is transmitted to the first servingcell to which PHR transmission resource is allocated for new uplinktransmission among the primary set serving cells.

The UE checks the valid bits among the C1 to C7 of the payload of thereceived A/D MAC CE at step 1420. The UE determines the bits in whichthe SCell indices match among the SCells configured in the non-primaryset as the valid bits and activates or deactivates the correspondingSCells based on the information of the valid bits. The UE assumes thatthe PUCCH SCell in the activated state always and thus ignores the bitcorresponding to the PUCCH SCell. For example, if the SCell 3 and SCell4 are configured in the non-primary set and if the SCell 3 is the PUCCHSCell, the UE determines C3 and C4 as valid bits and activates ordeactivates the SCell 4 depending on the value of C4. The UE starts orrestarts the sCellDeactivationTimer of the SCell instructed to beactivated and stops the sCellDeactivationTimer of the SCell instructedto be deactivated. If at least one SCell is activated by the A/D MAC CE,the UE triggers Power Headroom Report (PHR), which is transmittedthrough the first serving cell allocated the PHR transmission resourcefor new uplink transmission among the non-primary set serving cells.

The UE checks the valid bits among the C1 to C7 of the payload of thereceived A/D MAC CE at step 1425. The UE determines all bits related tothe currently configured serving cells as the valid bits and activatesor deactivates the corresponding serving cells based on the values ofthe corresponding bits. If at least one SCell is activated based on thereceived A/D MAC CE, the UE triggers Power Headroom Report (PHR), whichis transmitted to the first serving cell allocated the PHR transmissionresource for new uplink transmission among the serving cells.

In an embodiment, the random access in a SCell can be performed onlywhen the corresponding SCell is in the activated state. In theconventional method, the SCells are configured to operate in thedeactivated initially and then transition to the activated state whenthe activation command is received through the A/D MAC CE. If thismechanism is applied to the non-primary set serving cell withoutmodification, the random access delay problem occurs in the non-primaryset serving cell.

In an embodiment of the present invention, a certain SCell, e.g. PUCCHSCell, stays in the activated state when a predetermined condition isfulfilled independently of the receipt of the A/D MAC CE.

FIG. 15 is a diagram illustrating the PUCCH SCell configurationprocedure between the UE and the eNB.

In the description of an embodiment, the drift eNB 1510 may be referredto as eNB 2 1510.

Referring to FIG. 15, the serving eNB 1515 determines to add a SCell tothe UE at a certain time point at step 1520.

In this embodiment, if the UE 1505 is located in the area of the cellcontrolled by the eNB 2 1510, the serving eNB 1515 may determine to adda cell under the control of the eNB 2 1510 as a SCell and send the eNB 21510 a control message requesting to add the SCell at step 1525. Thecontrol message may include at least one of the informations listed intable 2.

If the SCell add request control message is received at step 1525, thedrift eNB 1510 determines whether to accept the request in considerationof at least one of the current load status and channel condition. If itis determined to accept the request, the drift eNB 1510 sends theserving eNB 1515 a control message including at least one of theinformations listed in table 3 at step 1530.

If the control message is received, the serving eNB sends the UE 1505 acontrol message instructing to add the serving cell at step 1535. Thiscontrol message may be transmitted to the UE 1505 through an RRC controlmessage. The RRC control message includes at least one of theinformations listed in table 4. The RRC control message also may includethe information on the random access in the PUCCH SCell. If anon-primary set serving cell is configured through this control message,the UE 1505 configures the non-primary set serving cell and sets itsinitial state to the deactivated.

At step 1540, the UE 1505 sends the serving eNB 1515 a response messagein replay to the message received at step 1535.

The UE 1505 establishes downlink synchronization with the newlyconfigured SCells at step 1545. In an embodiment, if the downlinksynchronization is established with the PUCCH SCell, the UE 1505 maytransition the state of the PUCCH SCell to the activated state.

The UE 1505 acquires System Frame Number (SFN) of the PUCCH SCell amongthe newly configured SCells at step 1550. In an embodiment, the SFN maybe acquired in the procedure of receiving the system information,particularly Master Information Block (MIB). The SFN is an integer andincrements by 1 at every 10 ms in the range from 0 to 1023. The UE 1505checks the PUCCH transmission of PUCCH SCell using the SFN and PUCCHconfiguration information. When a certain SCell is configured, if theSCell is the PUCCH SCell, the UE receives the MIB to acquire the SFNand, otherwise if the SCell is not the PUCCH SCell, uses the SFN of thePCell or PUCCH SCell without receipt of the SFN.

The serving eNB 1515 sends the drift eNB a downlink data forwardingrequest at step 1552.

If the above operation has completed, or in parallel with step 1550, theUE transmits a preamble through the PUCCH SCell at step 1555.

After transmitting the preamble, the UE 1505 monitors the PDCCH of thePUCCH SCell during a predetermined period determined in association withthe subframe at which the preamble has been transmitted at step 1560.The drift eNB determines whether there is any downlink schedulinginformation addressed to the RA-RNTI mapped to the time/frequencyresource used for transmitting the preamble and, if so, decodes thePDSCH based on the downlink scheduling information. The random accessresponse message received on the PDSCH includes a Random Access PreambleID matching the preamble transmitted by the UE, the drift eNB determinesthat the random access response message is the valid response message.

The UE 1505 adjusts the uplink transmission timing by applying theTiming Advance (TA) command included in the response message, generatesa MAC PDU based on the uplink grant included in the response message,and performs PUSCH transmission through the PUCCH SCell at step 1565.The MAC PDU may include the C-RNTI-NP of the UE and, if the drift eNB1510 receives the MAC PDU successfully, it assumes that the UE 1505 iscapable of transmitting/receiving uplink/downlink signals in the PUCCHSCell.

If the first random access procedure has completed successfully in thePUCCH SCell, the UE 1505 and the drift eNB 1510 activates PUCCHtransmission in the PUCCH SCell at step 1570. That is, the UE transmitsCSI and SRS on the PUCCH of the SCell at a predetermined timing. The UEassumes that the uplink data transmission is possible through the PUCCHSCell since when the random access procedure has completed successfullyand thus, if an uplink grant is received on the PDCCH, performs uplinktransmission based thereon. If the random access has completedsuccessfully, this may mean that the Contention Resolution hascompleted. The Contention Resolution is specified in 36.321. The drifteNB 1510 may instruct activation of the SCell, with the exception of thePUCCH SCell, using the A/D MAC CE.

FIG. 16 is a flowchart illustrating the UE operation of configuring andactivating the PUCCH SCell.

Referring to FIG. 16, the UE receives a control message, e.g. RRCconnection reconfiguration message, instructing to configure a SCell andconfigures the SCell at step 1605.

The UE sets the initial state of the SCell to the deactivated state atstep 1610.

The UE determines whether the configured SCell is the PUCCH SCell atstep 1615. If the configured cell is the PUCCH SCell, the procedure goesto step 1625 and, otherwise, step 1620.

The UE waits for receiving the A/D MAC CE indicating the activated stateof the SCell and, upon receipt thereof, activates the SCell at step1620.

The UE attempts downlink synchronization with the PUCCH SCell and, ifthe downlink synchronization is acquired, activates the PUCCH SCell atstep 1625. If the downlink synchronization with the PUCCH SCell has beenestablished already, the UE sets the state of the PUCCH SCell to theactivated state upon receipt of the SCell configuration command. Thatis, the UE may set the initial state of the PUCCH SCell to the activatedstate. The UE may activate the PUCCH SCell when the random access isprepared completely or when the random access procedure is triggered.

The UE initiates acquisition of SFN of the PUCCH SCell at step 1630. TheUE receives the Master Information Block (MIB) including the SFNinformation on predetermined time/frequency resource of the PUCCH SCell.The frequency resource may be 6 Resource Blocks (RBs) of the downlinkcenter frequency band. The time resource may be the n^(th) subframe ofevery radio frame.

The UE performs the SFN random access in the PUCCH SCell along with theSFN acquisition procedure simultaneously at step 1635.

If the random access completes successfully, the UE activates the PUCCHtransmission at a predetermined timing at step 1640. The predeterminedtiming may be the late time point between the random access completiontime point and the SFN acquisition time point.

Depending on the embodiment, the eNB may use different activationschemes for the primary set serving cell and the non-primary set servingcell. For example, the primary set SCells are configured initially inthe deactivated state while the non-primary set SCell are configuredinitially in the activated state.

FIG. 17 is a flowchart illustrating the UE operation of configuring andactivating the non-primary set serving cells.

Referring to FIG. 17, the UE receives a SCell configuration command atstep 1705.

The UE configures the SCell initially to be in the deactivated state atstep 1710.

The UE determines whether the configured SCell is a primary set servingcell at step 1715. If the configured cell is a primary set serving cell,the procedure goes to step 1720 and, otherwise, step 1730.

The UE waits for receiving the A/D MAC CE and, if the A/D MAC CEinstructing activation of the SCell, activates the SCell at step 1720.

The UE starts a sCellDeactivationTimer of the corresponding cell at step1725. If the A/D MAC CE instructing activation of the SCell is receivedat sf[n], the sCellDeactivationTimer starts at sf[n+m] where m is aninteger, e.g. 8, known to the eNB.

The UE waits for the acquisition of downlink synchronization with theSCell and, if the downlink synchronization is acquired, transitions thestate of the SCell to the activated state. If the downlinksynchronization has been already established in the SCell configurationphase, the UE may configure the SCell initially in the activated stateupon receipt of the SCell configuration command.

The UE starts sCellDeactivationTimer of the cell at a predeterminedtiming at step 1735. If the control message instructing SCellconfiguration is received sf[k], the sCellDeactivationTimer startssf[k+q]. Here, q may be a predetermined integer. The subframe determinedby q may be the subframe carrying the response message in replay to theSCell configuration control message.

FIG. 18 is a diagram illustrating the procedure of adding the primaryset and non-primary set serving cell and transmitting/acquiring systeminformation.

Referring to FIG. 18, in the mobile communication system composed of theUE 1801, the first eNB 1 1815, and the second eNB 1810, cells a, b, andc are controlled by the eNB 1, and the cells d and e are controlled bythe eNB 2. Under the assumption that cell a is the PCell of the UE, theeNB 1 attempts adding cell b to the UE additionally. In this embodiment,the description is made under the assumption that the eNB 1 1815 is theserving eNB and the eNB 2 1810 is a drift eNB.

The serving eNB 1815 determines to add the cell b as the SCell 1 at step1817. This decision may be made based on at least one of the channelcondition and the traffic of the UE 1805. Depending on the embodiment,the serving cell 1815 may determine the cell to be added as SCell.

The serving eNB 1815 sends the UE 1805 a control message includinginformation related to the SCell to be added to newly to the UE 1805 atstep 1820. Depending on the embodiment, the control message may betransmitted through the RRC connection reconfiguration message.

The SCell to be added newly is the cell under the control of the servingcell 1815, and the control message may include at least one of theinformations listed in table 1. The radioResourceConfigCommonSCell-r10includes a part of the system information of the corresponding SCell.For example, it includes at least one of the downlink bandwidthinformation, downlink HARQ feedback channel configuration information,uplink center frequency information, and uplink bandwidth informationthat are provided in MIB, SIB1, SIB2 of the SCell. Since the systeminformation of the primary set serving cell is managed by the servingeNB 1815, the eNB can transmit the system information in order for theUE 1805 to operation successfully in the SCell.

It is not necessary for the UE 1805 to acquire the system informationfrom SCell directly and to check the change of the system information atstep 1882.

After configuring the SCell, the UE 1805 may receive/transmitdownlink/uplink data through the PCell and the SCell 1 at step 1824.

The system information of the cell b changes at a certain time point atstep 1830.

The serving eNB 1815 sends the UE 1805 a control message to remove theSCell and perform reconfiguration at step 1835. Depending on theembodiment, the control message may be transmitted through the RRCconnection reconfiguration message, and the SCell of which systeminformation has been changed is removed and then reconfigured accordingto the control message.

In the primary set SCell, the serving eNB 1815 provides the systeminformation using the RRC connection reconfiguration message, and the UE1805 does not check the change of the system information of the SCell.If the system information of the non-primary set serving cell changes,the drift eNB 1810 requests the serving eNB 1815 to release/configurethe serving cell and sends the serving eNB 1815 the changed systeminformation, and the serving eNB 1815 provides the UE 1805 with thechanged system information through the serving cellrelease/configuration procedure.

The serving eNB 1815 determines to add a SCell to the UE 1805 at step1840. Depending on the embodiment, this determination may be made at anarbitrary time point and, in this embodiment, the cell e is determinedto be added. Depending on the embodiment, the SCell add message istransmitted to the drift eNB 1810 without determining the cell to beadded such that the drift eNB 1810 determines the SCell.

Particularly if the UE 1805 is located in an area of the cell controlledby the eNB 2 1810, the serving eNB 1815 determines to add a cellcontrolled by the eNB 2 1810 as the SCell and sends the eNB 2 1810 acontrol message requesting to add the SCell at step 1845. The controlmessage includes at least one of the informations listed in table 2.

If the SCell add request control message is received, the drift eNB 1810determines whether to accept the request in consideration of the currentload status. If it is determined to add the cell e as the SCell 2, thedrift eNB 1810 sends the serving eNB a control message including theinformation of table 2 at step 1850.

If the control message is received t step 1850, the serving eNB 1815sends the UE 1805 a control message instructing to add the serving cellat step 1855. The control message may an RRC control message whichincludes at least one of the informations listed in table 4. The controlmessage includes a part of the system information of the SCell to beadded newly, i.e. SCell 2.

The UE 1805 configures the SCell 2 using the information contained inthe received RRC connection reconfiguration control message, e.g. systeminformation of the SCell 2, and performs data communication through theSCell 2 at step 1860.

Afterward, the system information of the cell e changes at a certaintiming at step 1870.

The drift eNB 1810 sends a control message requesting the serving eNB1815 to remove and add back the SCell 2 at step 1875. This controlmessage may include new system information of the SCell 2.

The serving eNB 1815 sends the UE 1805 the RRC connectionreconfiguration message including the information provided by the drifteNB 1810 at step 1880.

In this embodiment, the UE 1805 removes and then configures the SCell 2again according to the information included in the control message. Atthis time, the new system information included in the control message isapplied.

The UE 1805 performs random access in the PUCCH SCell to notify of thefact that the new system information has been applied at step 1885. Ifthe random access procedure completes, the drift eNB 1810 assumes thatthe SCell 2 is configured completely and performs the subsequentoperation necessary.

In this present invention, if the non-primary set serving cell isremoved and then reconfigured through one RRC control message, i.e. ifthe serving cell of the same SCell index is removed and thenreconfigured with one message, the UE performs random access in thePUCCH SCell, although the non-primary set serving cell is not the PUCCHSCell, to report that the primary set serving cell has been reconfiguredsuccessfully.

A method for the UE to monitor to detect change of the systeminformation in a specific cell among the non-primary set serving cellsin order to reduce the delay caused by transmitting the new informationprovided from the drift eNB to the serving eNB is depicted in FIG. 19.

FIG. 19 is a diagram illustrating an alternative procedure of acquiringsystem information through primary set serving cell and non-primary setserving cell.

Referring to FIG. 19, steps 1917, 1920, 1922, 1924, 1930, 1935, 1940,1945, and 1950 may be performed in the same manners as steps 1817, 1820,1822, 1824, 1830, 1835, 1840, 1845, and 1850.

The serving eNB 1915 sends the UE 1905 a control message instructing toadd a serving cell at step 1955. Depending on the embodiment, theserving eNB 1915 may sends the UE 1905 a RRC control message. The RRCcontrol message includes at least one of the informations listed intable 4. The control message includes the information instructing toacquire a part of the system information of the newly added SCell, i.e.SCell 2 and monitor the system information. The information may betransmitted explicitly or analogized from other information. Forexample, if it is determined in advance for the UE to acquire the systeminformation on the PUCCH SCell (or non-primary set serving cell) andmonitor the system information, there is no need of the explicitinformation provision, and the UE determines whether to perform thesystem information acquisition/monitoring operation according to whetherthe SCell is the PUCCH SCell (or non-primary set serving cell) or not.

The UE 1905 configures the SCell 2 using the information included in theRRC connection reconfiguration control message, e.g. system informationof SCell 2, and performs the random access procedure with apredetermined SCell at step 1960.

After completing the random access procedure, the UE 1905 communicatesdata through the SCell at step 1965.

Afterward, the system information of Cell 3 changes at step 1970.Depending on the embodiment, the system information of the Cell e maychange at an arbitrary time point.

If the system information of the Cell e changes, the drift eNB 1910notifies the UE that the system information, particularly MIB, SIB1, andSIB2, has to be received newly in the corresponding SCell at step 1975.The drift eNB 1910 transmits the information on whether the systeminformation has been changed using the paging message or a predetermineddedicated MAC control message. In the case of using the paging message,the UE 1905 monitors the PDCCH of the PUCCH SCell, non-primary setserving cell, or the SCell for which system informationacquisition/monitoring has been instructed to detect the downlinkscheduling information addressed to P-RNTI. If the downlink schedulinginformation addressed to the P-RNTI is received, the UE decodes thePDSCH to acquire the paging message based on the scheduling informationand determines whether the paging message includes the systeminformation change information.

If the paging message includes the system information changeinformation, the UE 1905 acquires the system information of thecorresponding SCell from the start time of the next modification period.The modification period is specified in TS36.331. In the case of usingthe dedicated RRC control message or MAC CE, the UE decodes the PDSCHusing he downlink scheduling information addressed to C-RNTINP and, ifthe system information change MAC CE or dedicated RRC control message isreceived on the PDSCH, starts the system information acquisitionprocedure. The control information includes at least one of thefollowing informations. The system information includes the changedSCell identifier, changed system information type (e.g. indication ofthe system information changed among MIB, SIB1, and SIB2).

The UE 1905 acquires the system information of the corresponding SCellfrom the start time of the next modification period.

FIG. 20 is a flowchart illustrating the UE operation ofacquiring/monitoring system information of the primary set serving celland non-primary set serving cell.

Referring to FIG. 20, the UE receives a SCell configuration command atstep 2005. The control message includes information on the SCell to beadded newly, particularly the partial system information of the SCellsuch as downlink bandwidth information, downlink HARQ feedback channelconfiguration information, uplink center frequency information, anduplink bandwidth information.

The UE configures the SCell based on the SCell configuration informationsuch as downlink bandwidth information, and downlink HARQ feedbackchannel configuration information.

The UE checks whether the SCell is of requiring to acquire and monitorthe system information of the configured SCell at step 2015 and, if so,the procedure goes to step 2030 and, otherwise if not, step 2020. Forexample, if the configured SCell is the PUCCH SCell or non-primary setserving cell or is defined to perform system information acquisition andmonitoring in the SCell configuration information, this means that theSCell is of requiring system information acquisition and monitoring andthus the procedure goes to step 2030.

At step 2020, the UE performs data communication without acquiring ormonitoring the system information.

At step 2030, the UE acquires the MIB/SIB1/SIB2 of the SCell and updatesthe information of the same type as the information acquired at step2005 (e.g. downlink bandwidth information) selectively among theinformations included in the system information.

The UE monitors the system information to detect any change thereof atstep 2035. Although not shown in the drawing, the UE may perform datacommunication in the course of steps 2030 and 2035. The UE operation ofmonitoring the system information to detect change thereof has beendescribed with reference to steps 1975 and 1980 of FIG. 19.

FIG. 21 is a flowchart illustrating the UE operation of monitoring thesystem information to detect any change thereof in association with theprimary set serving cell and non-primary set serving cell.

Referring to FIG. 21, if a certain serving cell is configured at step2105, the procedure goes to step 2110.

If the configured serving cell is the PCell at step 2110, the proceduregoes to step 2115 and, otherwise, step 2130.

At step 2115, the UE monitors P-RNTI.

The UE receives the MAC PDU, i.e. paging message, addressed to theP-RNTI, at step 2120 and, if the paging message includessystemInfoModification set to True, starts receiving MIB/SIB1/SIB2 atthe start time of next modification period at step 2125.

At step 2130, the UE determines whether the configured serving cell is anon-primary set serving cell. Or PUCCH SCell. Or SCell for which systeminformation change monitoring is instructed. If so, the procedure goesto step 2135 and, otherwise, step 2150.

At step 2135, the UE monitors C-RNTI NP.

The UE receives a system information change MAC CE at step 2140.

If the system information change MAC CE is received, the procedure goesto step 2145. The system information change MAC CE is identified by apredetermined LCID and may include the information informing whichsystem information of which SCell has been changed.

At step 2145, the UE receives the system information of the SCell ofwhich the MAC CE indicates the system information has been changed at apredetermined time point. The predetermined time point may be the starttime of the next modification period of the corresponding SCell or thetime elapsed a predetermined period since the time when the systeminformation change MAC CE has been received successfully.

The UE skips the system information change monitoring procedure for thecorresponding SCell at step 2150.

A SCell may be added or removed according to the necessity of the drifteNB. At this time, if the UE notifies the drift eNB whetherconfiguration has completed or not immediately, it is possible to avoidperformance degradation caused by configuration delay.

FIG. 22 is a diagram illustrating entire operation of adding primary setand non-primary set serving cells and transmitting/acquiring systeminformation.

Referring to FIG. 22, in the mobile communication system composed of theUE 2205, the first eNB 1 2215, and the eNB 2 2210, cells a, b, and c arecontrolled by the eNB 1, cells d and e are controlled by the eNB 2. Inthis embodiment, the eNB 1 2215 is referred to as serving eNB, and theeNB 2 2210 is referred to as drift eNB.

The cell a is the PCell of the UE 2205, and the cell e is the SCell 2.

The eNB 1 2215 intends to configure a primary set serving cell, i.e. thecell b, as an additional SCell to the UE 2205 at step 2217.

The serving eNB 2215 sends the UE 2205 a message including theinformation on the SCell to be added newly at step 2220. This messagemay be transmitted through a control message called RRC connectionreconfiguration. The SCell to be added newly is a cell managed by theserving cell directly, and the control message includes at least one ofthe informations listed in table 1 per serving cell.

The UE 2205 configures the cell b as SCell 1 according to theconfiguration information and sends the serving eNB 2215 an RRCconnection reconfiguration complete control message at step 2222.

The serving eNB 2215 and the UE 2205 perform data communication throughthe PCell and SCell 1 at step 2224.

The drift eNB 2210 determines to configure the cell d as an additionalSCell to the UE 2205 at step 2226.

The drift eNB 2210 sends the serving eNB 2215 a control messagerequesting to configure the cell d as SCell 3 at step 2230.

The serving eNB 2215 sends the UE 2205 the RRC connectionreconfiguration message including the information provided by the drifteNB 2210 at step 2235. The UE 2205 adds the SCell 3 according to theinformation included in the control message.

The UE 2205 sends the serving eNB 2215 an RRC connection reconfigurationcomplete control message at step 2240. If it is recognized that the eNBwhich has transmitted the complete control message differs from the eNBof which the new serving cell has been configured, the UE 2205 sends thedrift eNB 2210 a configuration complete MAC CE at step 2245. Theconfiguration complete MAC CE may be identified by a predetermined LCIDand include the identifiers of the SCells added newly or removed. Or itmay include the information about completed configuration such as newSCell addition, old SCell removal, old SCell modification, PUCCHtransmission reconfiguration, and radio transmission resourceconfiguration.

If the MAC CE is received, the drift eNB 2210 starts data communicationthrough the newly configured SCell at step 2250. In an embodiment, steps2240 and 2245 may be in different temporal order. The UE 2205 mayperform step 2245 prior to step 2240, i.e. transmit the configurationcomplete MAC CE to the drift eNB 2210 before transmitting the RRCconnection reconfiguration complete control message so as to start datacommunication more promptly.

FIG. 23 is a flowchart illustrating the UE operation which has receivedthe RRC connection reconfiguration message in the primary set servingcell and non-primary set serving cell.

Referring to FIG. 23, the UE receives a RRC connection reconfigurationmessage at step 2305.

The UE performs RRC configuration reconfiguration based on the receivedRRC connection reconfiguration message at step 2310. In this embodiment,the RRC connection reconfiguration means the operation of reconfiguringthe radio transmission resource PUCCH transmission resource or layer 2configuration of a specific serving cell, new SCell addition, old SCellremoval, or old SCell modification.

The UE determines whether the RRC connection reconfiguration isassociated with a non-primary set at step 2315 and, if so, the proceduregoes to step 2330 and, otherwise, step 2320. If RRC connectionreconfiguration fulfils at least one of the following conditions, thereconfiguration is associated with the non-primary set.

The RRC connection reconfiguration is of adding, removing, or modify anSCell which is not a primary set serving cell

The RRC connection reconfiguration is of configuring, releasing, ormodifying PUCCH transmission in PUCCH SCell

The RRC connection reconfiguration is of configuring, releasing, ormodifying SRS transmission in the SCell which is not a primary setserving cell

The RRC connection reconfiguration is of configuring MAC associated withnon-primary set, e.g. modifying DRX configuration of non-primary set

The RRC connection reconfiguration is of modifying configuration ofnon-primary set logical channel

The UE generates an RRC connection reconfiguration complete message atstep 2320 and transmits this message to the primary set serving cell atstep 2325 to complete the procedure.

The UE generates a configuration complete MAC CE and RRC connectionreconfiguration complete message at step 2330.

The UE sends the non-primary set serving cell the configuration completeMAC CE at step 2335.

The UE sends the primary set serving cell the RRC connectionreconfiguration complete message at step 2340 to complete the procedure.

FIG. 24 is a block diagram illustrating a configuration of the UEaccording to an embodiment of the present invention.

Referring to FIG. 24, the UE according to an embodiment of the presentinvention includes a transceiver 2405, a controller 2410, amultiplexer/demultiplexer 2420, a control message processor 2435, andvarious higher layer processors 2425 and 2430.

The transceiver 2405 receives data and predetermined control signals onthe downlink channel of the serving cell and transmits data andpredetermined control signals on the uplink channel. In the case that aplurality of serving cells is configured, the transceiver 2405transmits/receives data and control signals through the plural servingcells.

The multiplexer/demultiplexer 2420 multiplexes the data generated by thehigher layer processors 2425 and 2430 and the control message processor2435 and demultiplexes the data received by the transceiver 2405, thedemultiplexed data being delivered to the higher layer processors 2425and 2430 or the control message processor 2435.

The control message processor 2435 is an RRC layer entity which takes anaction necessary for processing the control message received from theeNB. For example, the control message processor 2435 processes thereceived random access-related information and delivers the processingresult to the controller.

The higher layer processors 2425 and 2430 are established per service.The higher layer processor processes the data generated by the userservice such as File Transfer Protocol (FTP) and Voice over InternetProtocol (VoIP), the processing result being delivered to themultiplexer/demultiplexer 2420, and processes the data from themultiplexer/demultiplexer 2415, the processing result being delivered tothe higher layer service application.

The controller 2410 controls the transceiver 2405 and themultiplexer/demultiplexer 2420 to perform uplink transmission usingappropriate resource at an appropriate timing based on the schedulingcommand, e.g. uplink grants, received by the transceiver 2405. Thecontroller controls overall procedures associated with SCellconfiguration and DRX operation. In more detail, the controller controlsoverall operations of the UE AS described with reference to FIGS. 5 to23.

FIG. 25 is a block diagram illustrating an eNB according to anembodiment of the present invention.

Referring to FIG. 25, the eNB includes a transceiver 2505, a controller2510, a multiplexer/demultiplexer 2520, a control message processor2535, various higher layer processors 2525 and 2530, and a scheduler2515.

The transceiver transmits data and predetermined control signals on thedownlink channel of the serving cell and receives data and predeterminedcontrol signals on the uplink channel. In the case that a plurality ofcarriers is configured, the transceiver 2505 transmits/receives data andcontrol signals through the plural carriers.

The multiplexer/demultiplexer 2520 is responsible for multiplexing datagenerated by the higher layer processors 2525 and 2530 and the controlmessage processor 2535 or demultiplexing the data received by thetransceiver 2505, the demultiplexed data being delivered to the controlmessage processor 2535 or the controller 2510. The control messageprocessor 2535 processes the control message transmitted by the UE andtakes a necessary action or generates a control message to betransmitted to the UE, the generated control message being delivered tothe lower layer.

The higher layer processors 2525 and 2530 are established per serviceand processes the data from the S-GW or other eNB into RLC PDU, the RLCPDU being delivered to the multiplexer/demultiplexer 2520, and processesthe RLC PDU from the multiplexer/demultiplexer 2520 into PDCP SDU, thePDCP SDU being transmitted to the S-GW or other eNB.

The scheduler allocates transmission resource to the UE at anappropriate timing in consideration of the UE buffer status and channelstatus and controls the transceiver to process the signal to betransmitted to the UE and transmit the signal.

The controller controls overall operations associated with the randomaccess and SR transmission. In more detail, the controller performscontrol operations of the eNB as described with reference to FIGS. 5 to23.

It is to be appreciated that those skilled in the art can change ormodify the embodiments without departing the technical concept of thisinvention. Accordingly, it should be understood that above-describedembodiments are essentially for illustrative purpose only but not in anyway for restriction thereto. Thus the scope of the invention should bedetermined by the appended claims and their legal equivalents ratherthan the specification, and various alterations and modifications withinthe definition and scope of the claims are included in the claims.

Although various embodiments of the present disclosure have beendescribed using specific terms, the specification and drawings are to beregarded in an illustrative rather than a restrictive sense in order tohelp understand the present invention. It is obvious to those skilled inthe art that various modifications and changes can be made theretowithout departing from the broader spirit and scope of the invention.

What is claimed is:
 1. A method by a terminal in a communication system,the method comprising: receiving first control information for asecondary cell group on a primary cell group, the first controlinformation including information for at least one serving cell of thesecondary cell group; acquiring master information block (MIB) on afirst serving cell of the secondary cell group, a physical uplinkcontrol channel (PUCCH) being configured in the first serving cell;identifying system frame number (SFN) for the at least one serving cellof the secondary cell group based on the acquired MIB; and transmittinguplink control information on the first serving cell of the secondarycell group based on the identified SFN.
 2. The method of claim 1,further comprising: identifying synchronization information for downlinkof the first serving cell of the secondary cell group in response to thefirst control information.
 3. The method of claim 1, wherein the atleast one serving cell of the secondary cell group except for the firstserving cell is in deactivated state in response to the first controlinformation.
 4. The method of claim 1, wherein the uplink controlinformation includes at least one of a channel quality reporting,scheduling request configuration and sounding reference signalconfiguration.
 5. The method of claim 1, wherein the uplink controlinformation is transmitted in response to a procedure of a random accessassociated with the first serving cell of the secondary cell group.
 6. Amethod by a base station in a communication system, the methodcomprising: transmitting first control information for a secondary cellgroup on a primary cell group, the first control information includinginformation for at least one serving cell of the secondary cell group;transmitting master information block (MIB) on a first serving cell ofthe secondary cell group, a physical uplink control channel (PUCCH)being configured in the first serving cell; and receiving uplink controlinformation on the first serving cell of the secondary cell group basedon system frame number (SFN) identified based on the MIB, the SFN beingidentified for the at least one serving cell of the secondary cellgroup.
 7. The method of claim 6, wherein synchronization information fordownlink of first serving cell of the secondary cell group is identifiedin response to the first control information.
 8. The method of claim 6,wherein the at least one serving cell of the secondary cell group exceptfor the first serving cell is in deactivated state in response to thefirst control information.
 9. The method of claim 6, wherein the uplinkcontrol information includes at least one of a channel qualityreporting, scheduling request configuration and sounding referencesignal configuration.
 10. The method of claim 6, wherein the uplinkcontrol information is received in response to a procedure of a randomaccess associated with the first serving cell of the secondary cellgroup.
 11. A terminal in a communication system, the terminalcomprising: a transceiver; and at least one processor coupled with thetransceiver and configured to: receive first control information for asecondary cell group on a primary cell group, the first controlinformation including information for at least one serving cell of thesecondary cell group; acquire master information block (MIB) on a firstserving cell of the secondary cell group, a physical uplink controlchannel (PUCCH) being configured in the first serving cell; identifysystem frame number (SFN) for the at least one serving cell ofassociated with the secondary cell group based on the acquired MIB; andtransmit uplink control information on the first serving cell of thesecondary cell group based on the identified SFN.
 12. The terminal ofclaim 11, wherein the at least one processor is further configured toidentify synchronization information for downlink of the first servingcell of the secondary cell group in response to the first controlinformation.
 13. The terminal of claim 11, wherein the at least oneserving cell of the secondary cell group except for the first servingcell is in deactivated state in response to the first controlinformation.
 14. The terminal of claim 11, wherein the uplink controlinformation includes at least one of a channel quality reporting,scheduling request configuration and sounding reference signalconfiguration.
 15. The terminal of claim 11, wherein the uplink controlinformation is transmitted in response to a procedure of a random accessassociated with the first serving cell of the secondary cell group. 16.A base station in a communication system, the base station comprising: atransceiver; and at least one processor coupled with the transceiver andconfigured to: transmit first control information for a secondary cellgroup on a primary cell group, the first control information includinginformation for at least one serving cell of the secondary cell group;transmit master information block (MIB) on a first serving cell of thesecondary cell group, a physical uplink control channel (PUCCH) beingconfigured in the first serving cell; and receive uplink controlinformation on the first serving cell of the secondary cell group basedon system frame number (SFN) identified based on the MIB, the SFN beingidentified for the at least one serving cell of the secondary cellgroup.
 17. The base station of claim 16, wherein synchronizationinformation for downlink of the first serving cell of the secondary cellgroup is identified in response to the first control information. 18.The base station of claim 16, wherein the at least one serving cell ofthe secondary cell group except for the first serving cell is indeactivated state in response to the first control information.
 19. Thebase station of claim 16, wherein the uplink control informationincludes at least one of a channel quality reporting, scheduling requestconfiguration and sounding reference signal configuration.
 20. The basestation of claim 16, wherein the uplink control information is receivedin response to a procedure of a random access associated with the firstserving cell of the secondary cell group.